BG103970A - Mixture of substances containing compounds of vinyl groups and stabilizers - Google Patents

Abstract

The invention relates to a mixture of substances including one or more compounds with vinyl groups as component (A), and as component (B) - stabilizer containing one or more easily volatile nitroxyl compounds as component (b1), one or more not easily volatile nitroxyl compounds as component (b2), optionally one or more aromatic nitrocompounds as component (b3), optionally one or more iron compounds as component (b4). The invention also relates to stabilizers (B) containing the components (b1) & (b2), (b1), (b2) and (b3), (b1) (B2), (b4) and (b1),(b2), (b3) and (b4), and to a method for the inhibition of the premature polymerization of compounds containing vinyl groups during their refining or distillation by the addition of either stabilizer (B) or components from it as individual substances or at least as two groups of components. 10 claims

Description

Technical field

The present invention relates to a mixture of substances which contains one or more compounds with vinyl groups, as component (A) and as another constituent stabilizer (B), which contains one or more volatile nitroxyl compounds of secondary amines, as component ( B- |), one or more volatile nitroxyl compounds of secondary amines, as component (b3), optionally one or more aromatic nitro compounds, as component (b3), and optionally one or more iron compounds, as component (b) | 04).

The invention further relates to stabilizers (B) containing components (b- |) and (b3), (b- |) and (b3) and (b3), (bj) (b3) and (bd), as and (b), (b3), (b3) and (bd), and to a method of inhibiting the premature polymerization of compounds containing vinyl groups during their purification or distillation by the addition of stabilizer (B), or by the addition of stabilizer (B) components as single substances or as at least two groups of components.

BACKGROUND OF THE INVENTION

Many unsaturated compounds are known to tend to increase the temperature to generally radical

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ongoing polymerization. For example, vinyl aromatic compounds such as styrene or α-methylstyrene must be stabilized with suitable compounds to prevent premature polymerization in the distillation treatment of these raw materials for industrial purposes. Usually, stabilizers or polymerization inhibitors are added to the crude products to be distilled before or during the purification step. Despite these precautions, noticeable amounts of polymers are obtained. In individual cases, especially during interferences in the production process during purification or distillation, complete polymerization of the available monomers or monomer mixtures may occur. As a result, production becomes more expensive, due to the high cost of treatment and the production of waste.

In the patent descriptions of the Soviet Union numbered 1,027,150,

Nos. 1,558,888 and 1,139,722 describe the stabilization of styrene using nitroxyl or benznitroxyl compounds.

4-Acylaminopiperidine-N-oxyl derivatives have been used in the earlier German patent application 19 510 184.7 to stabilize radical polymerizing monomers.

An older German patent application DE 19 609 312.0 describes a composition comprising monomers with vinyl groups together with at least one N-oxyl compound per second amine, wherein the latter does not contain hydrogen atoms at the N-linked Satomi.

Mixtures of vinyl aromatic compounds with ethereally inhibited nitroxyl compounds that are activated by traces of oxygen are described in WO 96/16921.

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Japan-patent Hei 1-165 534 discloses l-piperidyloxy derivatives as inhibitors of styrene polymerization. U.S. Patent 3,733,326 discloses the inhibition of polymerization of vinyl monomers by the addition of compounds that are radical precursors.

Mixtures of nitroxyl and nitro compounds are described in U.S. Patent No. 5,254,760 and in earlier German patent application 19 622 498.5, which are used to stabilize vinyl aromatic compounds, respectively, of vinyl group monomers during their purification and distillation.

Mixtures which, in addition to vinyl group compounds, also contain nitroxyl compounds and iron compounds, and optionally nitro compounds and stabilizers, are described in the earlier German patent description 19 651 307.3.

The action of the stabilizers described in these descriptions, as well as the stability of the added monomer mixtures are good, whereby a greater retention of the nitro compounds results in improved retention as described in the earlier German patent description 19 622 498.5 . Also, the presence of iron compounds in the stabilizers, as described in earlier German patent application 19 651 307.3, significantly improves their action. In the case of interruption of the introduction of the monomers and the stabilizing additive into the column, these stabilizers provide an improved time-delayed action until the initiation of a massive polymerization reaction.

For all stabilizers so far, the main focus has been on stabilizing the bottom of the column, however, stabilizing those in the vapor phase.

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monomers are neglected. An acceptable way of doing this is to disperse the stabilizers used in the bottom of the column into the carrier fluid, such as e.g. in the monomer mixture to be distilled and / or wetted on the walls of the columns, e.g. also stabilizer-mixed solvents. A similar distribution of the gas phase stabilizer and thus effective stabilization during distillation / purification by such measures is not sufficiently certain.

However, since in these industrial processes even small portions of polymerizates lead to the addition of large quantities of unwanted by-products, there is a need for even more active polymerization inhibitors. It is also desirable to reduce the proportion of nitro compounds in terms of improved processing by maintenance personnel and to reduce potential environmental contamination.

Therefore, there is a task to create mixtures of compounds with vinyl groups that are stabilized in both liquid and vapor phases, and are even more active against the process of premature polymerization during purification or distillation.

SUMMARY OF THE INVENTION

It has now been found that in a preferred way this problem can be solved by mixtures of substances which contain:

(A) compounds with one or more vinyl groups; (B) a stabilizer containing

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(B-j) nitroxyl compound of a secondary amine which does not contain hydrogen atoms at α-C atoms, the vapor pressure of which at the boiling point of the lowest boiling compound with vinyl groups of component (A) is from 0.01 to 50% relative to the vapor pressure of the lowest boiling compounds with vinyl groups of component (A) or a mixture of nitroxyl compounds of secondary amines which do not contain hydrogen atoms at the α-C atoms in which the vapor pressure of the highest boiling point nitroxyl compound at boiling point n and the lowest boiling compound with vinyl groups of component (A) is from 0.01 to 50% relative to the vapor pressure of the lowest boiling compound with vinyl groups of component (A), (b £) a nitroxyl compound of a secondary amine, which does not contain hydrogen atoms on α-C atoms, the vapor pressure of which at the boiling point of the highest boiling compound with vinyl groups of component (A) is less than 0.01% relative to the vapor pressure of the highest boiling compound with vinyl groups of component (A) or a mixture of nitrox Secondary amine compounds which do not contain hydrogen atoms at the α-C atoms, in which the vapor pressure of the lowest boiling nitroxyl compounds at the boiling point of the highest boiling compound with vinyl groups of component (A) is less than 0.01% relative to the vapor pressure of the highest boiling compound with the vinyl groups of component (A), with (b-0 and F2), respectively, being taken into account the vapor pressure of the corresponding pure nitroxyl compound and the vapor pressure of correspondingly pure vinyl aromatic • ·

913.99-PB compound, at the boiling point of that correspondingly pure vinyl aromatic compound, (b3) optionally one or more aromatic nitro compounds, (bg) optionally one or more ferrous compounds.

To simplify the language expression in the following description, the component (bf), respectively, the component (bp) will be referred to as the volatile and non-volatile component and the resulting nitroxyl compound will be referred to as the volatile nitroxyl compound (or mixture of volatile nitroxyl compounds) respectively as the volatile nitroxyl compound. compound (or mixture of volatile nitroxyl compounds).

A mixture of substances which contains, as a constituent (A), vinyl group compounds of formula la, is preferred

wherein

R ¹ is hydrogen, C 1 -C 4 -alkyl, C 1 -C 4 -alkenyl, carboxy, formyl, sulfo, hydroxy, amino or nitro,

R2 θ With p-Cd-alkenyl and / or vinyl groups of formula lb

1b, in which

R 3 is hydrogen, C 1 -C 4 -alkyl R ⁴ is C 1 -C 4 * alkenyl.

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The C1-C4-alkyl groups of the residues R ¹ and R 3 may be methyl, ethyl, propyl, 2-propyl, 1-butyl, 2-butyl, 2-methyl-1-propyl, and tert. butyl. As C -C-alkenyl groups of the radicals R ^1, R ³ and R ⁴ also may be considered residues vinyl 1propenil, 1-butenyl, 1-methyl-1-ethenyl, 1-methyl-1propenil, 2- methyl-1-propenyl (isobutenyl) and 1-ethyl-1-ethenyl. Suitable compounds of formula Ia, for example, are styrene, α-methylstyrene, p-, m-, o-nitrostyrene, p-, m-,

o-styrene sulfonic acid, p-, t-, o-vinyltoluene, p-, t-, vinylbenzene, p-, t-, o-vinylaniline, p-, t-, o-vinylphenol, whereby of the isomers of the vinyl aromatic compounds in practice, the o-isomer, if obtained at industrial scale at all, is only produced in limited quantities.

The compounds of formula lb are, for example, the following:

2-, 3-, 4-vinylpyridine or also various isomers of methylvinylpyridines, the most technically important being 2methyl-5-vinylpyridine. Of the vinylpyridine isomers as the most

Important products for industrial production can be mentioned above all 2- and 4-vinylpyridines.

Of course, mixtures of compounds of formula Ia or of compounds of formula Ib, or also mixtures of compounds of formulas Ia and Ib, may also be mentioned among the mixtures according to the invention.

Another preferred mixture of substances contains as constituent (A) compounds containing vinyl groups of formula II

CH ₂ - CZ ⁴ -QZ ¹ (1b) in which

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Q means a simple chemical bond, oxygen or -NZ2- group,

Oh

II _ of 3

Означава1 means the radicals C Z or -Z

Z 2, Z ⁴ are each hydrogen, C 1 -C 4 -alkyl,

Z ³ is hydrogen, hydroxy, cyano, C 1 -C 3 -alkoxy, C 1 -C 4 -alkyl or a residue which together with Ζ ² or Ζ ⁴ forms a saturated or unsaturated Οθ-, Cd-, C5- or Οθ-alkylene bridge, in which up to two of

carbon atoms that are not adjacent to each other can be replaced by Ν, ΝΗ,

N (C 1 -C 6 -alkyl), N (Cg-C-1-aryl) or with oxygen.

When Q in formula II means a simple chemical bond, the Z ¹ group is either the radical -CO-Z ³ or only the Z ³ group. The residues Z ³ are primarily hydroxy and C 1 -C 3 -alk

oxy groups, such as e.g. methoxy, ethoxy, propoxy, tert. butoxy or n-butoxy groups, but also 2-ethylhexoxy and in the latter case a cyano group.

Z ⁴ is hydrogen or a C 1 -C 4 -alkyl group, preferably hydrogen or methyl. In the mixtures according to the invention, preferred compounds (A) of formula II are acrylic acid, methacrylic acid, the corresponding methyl, ethyl, propyl, tert-butyl, norm. butyl and 2-ethylhexyl esters of these acids, as well as methacrylic acid acrylonitrile and nitriles.

In addition, the compounds (A) of formula II, which are an integral part of the mixtures according to the invention, may contain oxygen as a substituent Q. Of these compounds are preferred vinyl esters in which the Z ¹ group corresponds to the CO-Z1 radical, and vinyl ether in which the group Z ^ is identical with the group Z ^3, and where Z ³ is preferably a C | -C alkyl group, such as. methyl, ethyl, normal propyl, isopropyl, normal butyl, isobutyl, secondary butyl, tert. butyl or 2-ethylhexyl.

When the variable Q stands for the group -NZ ² -, το Z ¹ is preferably the group -CO-Z ³ .

As residue Z ³ , in addition to those mentioned above, such residues are also taken into account, e.g. together with the group -NZ ² form a saturated or unsaturated 5- to 7-membered ring. Examples of such ring systems are:

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and in particular N-pyrrolidinonyl or N-caprolactamyl moiety.

The Ν (Οθ-Ο- | θ-aryl) introduced into the residues of the group Ζ ³ ΟθCjQ-aryl groups preferably comprise phenyl groups which may be substituted by one or more C 1 -C 4 -alkyl groups. In the case of two or more substituents, the sum of the number of their C atoms must not exceed four. Exemplary substituents on the benzene ring are about three methyl groups, one methyl and one propyl group, or just one third only. butyl group. Other examples of C 1 -C 4 alkyl residues that may also be present in the N (C 1 -C 6 -alkyl) residues of the Z ³ group are already mentioned above. In addition to naphtha, naphthyl residue is considered as Swaril.

Other preferred compounds (A) in the mixtures of substances according to the invention are N-vinylformamide, N-vinyl-2-pyrrolidone, and vinyl-e-caprolactam.

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For the selection of suitable nitroxyl compounds as constituents (b-j) and (b £) of the stabilizer (B), it is appropriate to proceed from the vinyl groups of component (A) which have the purest substances lowest , respectively the highest boiling point (at respectively the same normal pressure p). These so identified compounds are referred to as? - respectively axes 2> ^and their boiling points are denoted T- | (p) and Ϊ2 (ρ). As the boiling points available are often given for normal pressure (1013 hPa), for volatile, respectively volatile compounds α- |, respectively «2 · with vinyl groups, p (a- |) = P (« 2) = P = 1013 hPa and

Τι (p) <m ₂ (p), respectively, the so-called low, respectively high boiling. For a volatile nitroxyl compound as component (bi), hereinafter designated as βι, according to the invention, the dependence

0.0001. p (<* 1, T-j) <ρ (βι, T- |) <0.50. p (a- |, T-) (1) and for a non-volatile nitroxyl compound, as component (62), hereinafter referred to as β2 &apos; according to the invention, can be generally written as follows

Ρ (β2 · ^t 2) <0-0001 · Ρ («2 · ^t 2) ( ² ) where p (a- |, T-), p (a.2>T2)> ρ (βΐ> Tj ) and ρ (β2, T2) denote (vapor pressures of pure compounds α- |, a.2, β, and β2 · respectively at temperatures T- | and Ϊ2- When these vapor pressures correspond to normal pressure (Referenzdruck) of 1013

Ϊ hPa, then the dependencies (1) and (2) must be processed as follows:

0.0001. 1013 hPa with ρ (β- |, T-j) ά 0.50. 1013 hPa (Γ) and

φφ φφ • φ φ φ φ φ φ φ φ ΦΦ φ φ ΦΦΦΦ • φ ΦΦ φ φ ΦΦΦΦ 913.99-PB φ φ φ φ φ φ φ φ φ φ · φ ΦΦΦ φ φ φ φ ΦΦ ΦΦ ΦΦΦ φφ φφ · Φ φφ 11 Ρ (β2 · ^t 2) <0-0001 .1013 hPa (2 '). When more volatile nitroxyls are used compounds (β1ch, β ² ι, β ³ 1 ...), such as component (b- |) and more

volatile nitroxyl compounds (β ¹ 1, β ² -, β ³ - | ...), as a component (b2) of the stabilizer (B), these compounds according to the invention, respectively, should be individually and as pure compounds.

to meet of dependencies (1) and (2), i.e. 0.0001  P («1, . B) <. ρ (β1 ₁ , Tt) 0.50  Ρ («1. Τ1) 0.0001 • P (ah . T1) ρ (β ² 1. Τ ·,) <0.50 • Ρ («1. Τ1) 0.0001 • Ρ ( ^α 1. . B) < ρ (β ³ Ί, Τ- |) 0.50  Ρ («1, ΊΊ)

ρ (β ¹ 2 ' ^t 2) <0 0001 p («2- ^t 2)

Ρ (β ² 2 · ^t 2) <0.0001. p (σ2> ^ 2) ρ (β ³ 2 · T2) <0.0001. ρ (α, 2 <^ 2)

where, naturally, when ρ (α- |, Τ · |) = p (a2> T2) - 1013 hPa holds, the relations (D) and (2 ') can be assigned.

In distillation, e.g. (ideally) isothermal conditions exist, so that for the lowest boiling and the highest boiling compounds with vinyl groups a- (and respectively a, 2> it can be written ρ (α.η, T- |) = p ( ot- |, T), respectively

Ρ («2 · ^t 2) = Ρ ( ^α 2« Ο

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in addition, the dependence ρ (α- |, T) = ρ («ι) <p (<X2, T) = p (« 2).

at T- | = Ϊ2 = T.

For the observed temperatures (in the vapor phase) T (= T - = Ϊ2), the dependences (1) and (2) according to the invention are obtained according to the invention, respectively.

0.0001. p (a- |) s ρ (β- |, T) = ρ (β- |) and 0.50. p (a- |) and

p (β 1, T) <0.0001. p (a.2), wherein p (a- |), p (a2), ρ (βι) and ρ (β2) represent the vapor pressures of the respective pure substances α- |, os2> Pl ^and P2 ^{N N} the corresponding temperature T.

For guidance in the selection of suitable nitroxyl compounds, such components (β-j) and (β2) · may serve as vapor pressure curves, as well as the corresponding data on the compounds with vinyl groups (A), which should be stabilized as in liquid and vapor phase. In most cases, the vapor pressure curves of the latter compounds can be found in the available literature, while the data for the first of the compounds are generally not found. Determination of vapor pressure as a function of temperature is, however, easily easily routinely performed for most of the compounds, so as a rule these data can be provided by those skilled in the art for a short time. In enterprises engaged in the distillation / purification of compounds with vinyl groups, they represent the basic operating parameters.

If the master data is available for a compound, e.g. evaporation heat and boiling point at a given pressure can be calculated by the Clausius equation-

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Clapeyron by extrapolation and other pairs of pressure / temperature indicators.

Nitroxyl compounds which can be used as volatile components (b-C or as volatile components (bp) can be taken, for example, from the older German patent application 196 51 307.3. As a general rule, the choice can be made in accordance with The molar mass of the nitroxyl compound Thus, typically, high molecular weight compounds are more volatile, eg also the nitroxyl compounds which contain two or more in the molecule cited above, cited above 196 51 307.3. -M-oxyl-2 , 2,6,6-tetramethylpiperidine units are more volatile than compounds with a lower molar mass, e.g., those of the above-cited German patent application nitroxyl compounds which contain only one 1-M-oxyl in the molecule The 2,2,6,6-tetramethylpiperidine unit, or also N-oxyl compounds of the formula described in this patent application, however, in all cases where, in the earlier German patent application, the substituents R are aralkyl or aryl groups, rather than lower alkyl groups, it should be cautioned lags that once again it is a harder volatile nitroxyl compounds.

• ft

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However, since volatility depends only partially on the molar

mass, but also to a great extent the structural features of particular compounds, such as e.g. by the presence of polar groups, by intramolecular and intermolecular interactions, etc., as already stated, the molar mass of the nitroxyl compounds in question can only serve as an initial consideration. Whether a compound is suitable for use as a component of the component (b- |) or of the component (bp) should be evaluated first and foremost from the perspective of the vinyl groups of the component (A) that is to be stabilized. A good starting point is, as a rule, the easily identifiable boiling point of the nitroxyl compound, so that the compound has a boiling point, optionally also under reduced pressure, as compared to the boiling point e.g. of the vinyl group compound, respectively, with those of the vinyl group compounds. Using the Pictet-Trouton rule and the Clausius-Clapeyron equation, the pressure / temperature estimates deviating from the specified boiling point can be made. The Pictet-Trouton rule (often referred to as the Trouton rule only) indicates that the molar entropy of evaporation has a value of about 88 J. mol ^- *. K'1.

This rule is generally subject to the most frequent non-polar substances. However, deviations from the rule are found in strongly associated compounds.

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According to the invention, one or more compounds of the formula are preferably used as the volatile component (b- |)

Sha,

wherein

R ⁵ is hydrogen,

R 6 is hydrogen, hydroxy, C 1 -C 4 alkoxy, C 1 -C 8 acyloxy, three (C 1 -C 4 alkyl) silyloxy or CR ⁵ R ⁶ denote together a carbonyl group and as a volatile component (b 2) preferably one or more compounds of formula 11b are used

wherein

X is oxygen or R 1 -N,

A e Οθ-Ο · | 2-alkylene, and, it bis (carbonyloxy) Ce-C ·] 2 ^'para alkyleneaminoalkylene, α, ω-Οθ-Ο- ] 2'Diatsil, 1,2-, 1,3- or 1,4- phenylene, phthaloyl, butoxy, 2-butoxy, 2-methylpropoxy (isobutoxy), and tert.

isophthaloyl or terphthaloyl,

R7 _is hydrogen, C1-C4-alkyl or C1-C6-acyl.

The C1-C4-alkoxy groups of the residue R ⁶ of compound IIIa include methoxy, ethoxy, propoxy, 2-propoxy, ···

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butoxy. The C1-C6-acyloxy groups of the residue R ⁶ are to be understood as formate, acetate, propionate, butanoate, pentanoate (valerate), hexanoate (capronate) and their isomeric groups, such as e.g. 2-methylpropionate (isobutanoate), 3-methylbutanoate (isovalerate), 2-methylbutanoate, neopentanoate or 2-, 3-, 4-methylpentanoate (valerate). Tri- (C 1 -C 4 -alkyl) silyloxy groups of the residue R 6 are preferably meant tri-substituted silyloxy groups having the same C 1 -C 4 alkyl groups. The C1-C4-alkyl groups are those already mentioned above when determining the values of the C1-C4-alkoxy groups of the alkyl moieties. For example, the following residues are considered silyloxy groups:

(H ₃ C) ₃ Si-O-, (H ₅ C ₂ ) ₃ Si-O- or [(H ₃ C) ₃ C] ₃ Si-O-.

In some cases, mixed substituted silyloxy residues, such as e.g.

CH ₃ CH ₃

--O - Si-- C --SN ₃ ^or --O CH ₃ CH ₃ CH ₃

Si - dream ₃ dream ₃ dream dream ₃

Examples of volatile nitroxyl compounds as an integral part of the component (L- |) are

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9 9 9 99 99

Examples of C 1 -C 4 -alkyl groups that may be present as the R ⁷ residue in the compounds of formula IIIb have already been commented upon in clarifying the meanings of the R ⁶ residue in the compounds of the formula Illa. Accordingly, as the C 1-10-acyl groups of the R ⁷ residue, the acyloxy groups of the R ⁶ residue mentioned above are used. The Cg-Cf 3-alkylene, a, 10 -bis (carbonyloxy) -C 6 -C 3 -alkylene and α, ω-Οθ-Οι 3-diacyl groups referred to in group A are preferably straight chain hydrocarbons, such as - (CH3) | -, -OCO- (CH3) _t -COO- and also - (CO) O- (CH3) _n -O (CO) - (wherein I, m and η denote integers from 6 to 12 , 4 to 10 and respectively 6 to 12). It is also possible for bridges A to have branched carbon chains.

As volatile nitroxyl compounds which can be used as building blocks for the component (b3), for example,

ShShMMM

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· · · · · · · · · · · · · · · · · · · · · · ·

n, p CH ₃ n ₃ sec CH3 ³ \ / 0 0 V / • ° L Mr II II -co- - (CH ₂ ) _P - OC- - ° m — about · / B ^ C \ sn ₃ in dream ₃ dream ₃

n, p CH3 A 0 • ο — N > -N — CO— (CH ₂ ) _n - / n ₃ sec dream ₃ R (R = H, CH ₃ )

n, with ³ \ CH, / H ₃ With CH 3 / -Y  O- / > - N <CH ₂ )] - N-- V. / CHO CHO H ₃ sec dream ₃ CH ₃ ^CH 3

OOS— (CH _? ) - vol

OOS

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The indices I, m and η may have the above numerical values.

Particularly suitable compounds for use are the following: bis (1-N-oxyl-2 ₁ 2,6,6-tetramethylpiperidin-4-yl) -adipate, bis (1-N-oxyl-2,2,6,6-tetramethylpiperidine) -4-yl) -sebacinate, Ν, Ν'-όποΟ-N-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) -

adipinamide,

N, N'-6nc (1-M-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacinamide,

N, N'-6nc (1-M-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) -1 \ 1, Mbis-formyl-1,6-diaminohexane.

The compounds of the formulas Illa and 11lb are readily available or may be commercially available, such as the compound

HE

H ₃ s n ₃ s

(Tempoi ”),

-Sn ₃

CH3

Huels and can be obtained

913.99-PB ···· • · ·· • · ·· • · ·· «• · ·· ··· · • ·· ··· · • · • ·· • · ··· ···· · The manufacturer is used to prepare the corresponding dimeric compounds of formula 11b.

On the other hand, the first underlying the structure of the compounds Illa and IIIb piperine derivatives can also be obtained and at a subsequent oxidation step, e.g. p

hydrogen peroxide to be converted to the corresponding nitroxyl compounds. Examples of such preparation methods can be found in the older German application 196 51 307.3 and in the literature cited therein.

Said volatile or, respectively, volatile compounds of formula Illa or IIIb are preferably introduced into a mixture of substances which already contains as a constituent (A) the above-mentioned vinyl group compounds of formulas la and / or Ib, as well as of formula II. Compounds of the formulas Illa and IIIb can be used, but also any other compound containing vinyl groups whose boiling points and vapor pressures meet the performance requirements of the nitroxyl compounds of the invention.

In addition to constituent (A) and stabilizer (B), one or more aromatic nitro compounds can also be used in the mixtures of substances according to the invention, as well as optionally one or more iron compounds. Suitable nitro compounds are described e.g. in an older German patent application 196 51 307.3. In particular, they can be used e.g. compounds 1, 3-dinitrobenzene, 1,4-dinitrobenzene, 2,6-dinitro-methylphenol, 2-nitro-4-methylphenol, 2,4,6-trinitrophenol, 2,4-dinitro-1-naphthol, 2,4-dinitro -6-methylphenol, 2,4-dinitrochlorobenzene, 2,4-dinitrophenol, 2,4-dinitro-6-sec. butylphenol, ·· ·· • · · · · · · · · · · · · · · · · · · · ·

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• ·· ·· · « ·· · · • • • · • · • • • · • · · ··· ··· • · • • ··· ···· »· • e

4-cyano-2-nitrophenol or 3-iodine-4-cyano-5-nitrophenol. Preferably, aromatic nitro compounds such as 2-nitro-4-methylphenol, 2,4-dinitro-6-sec are used. butylphenol, respectively, 2,4-dinitro-6-methylphenol.

Iron compounds are also described in older German patent application 196 51 307.3. They are in particular iron compounds of the groups:

a) ferrous carbonyl compounds and carbonylferates,

b) organometallic ferrous carbonyl compounds,

c) unsubstituted and substituted ferrocene,

d) iron compounds with ligands containing as donors alone or in mixtures oxygen, nitrogen, sulfur or phosphorus,

e) Iron halide and iron pseudohalide compounds.

Preferably, the iron compounds of groups a) and b) are used and the compounds of group d) are particularly preferred. Of the latter group, iron complexes with heteroanulins (e.g. azoanulenes) such as e.g. iron dibenzo [b, i] -1,4,8,11-tetraaza- (1,4) anulene (Fe (taa)) or iron complexes with (substituted and / or benzanilated) phthalocyanines. The compounds are also shown by their formulas as follows:

(Fe (taa))

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In addition, the mixture of substances according to the invention may also contain, e.g. one or more additional stabilizers in the group of aromatic nitro compounds, phenothiazines, quinones, hydroquinones and their ethers, phenols, and also their esters, hydroxylamines and phenylenediamines.

As aromatic nitro compounds are meant e.g. rnitrosophenol, p-nitroso-o-cresol or p-nitroso-M, M'-diethyl

aniline.

Other stabilizers may also be substituted phenols or hydroquinones, such as e.g. the following:

4-tert-butylpyrocatechin, methoxyhydroquinone, 2,6-di-tert. butyl-4-methylphenol, n-octadecyl-beta- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate, 1,1,3-tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane , 1,3,5-trimethyl-2,4,6-tris- (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 1,3,5-tris- (3,5-di-tert butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris- [beta- (3,5-di-tert-butyl4-hydroxyphenyl) propionyloxyethyl] isocyanurate, 1,3,5-tris (2,6-dimethyl) -3-hydroxy-4-tert-butylbenzyl) isocyanurate or pentaerythritol-tetrakis- [beta- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate].

• ·

913.99-PB • · · ·

According to the invention, a stabilizer (B) which contains, as components (b- 1) and (62), respectively, one or more nitroxyl compounds of formulas Illa and IIIb is preferred.

Furthermore, according to the invention, a stabilizer (B) is claimed which, in addition to compounds of formulas Illa and I lib (as components (b-1) and (b2)), also contains one or more aromatic nitro compounds, as component (b-3).

Also claimed according to the invention is a stabilizer which, in addition to compounds of formulas Illa and IIIb, also contains one or more iron compounds as component (64).

The invention also claims a stabilizer which, in addition to compounds of formulas Illa and IIIb, contains one or more aromatic nitro compounds as well as one or more iron compounds, such as components (b3) and (b4). Examples of suitable nitroxyl compounds, aromatic nitro compounds, and iron compounds have already been mentioned above.

If desired, said stabilizers (B) according to the invention may also contain other additives, such as e.g. those already mentioned above as stabilizers.

Said stabilizers (B) comprise the components (b-j) and F2, respectively, in an amount of from 1 to 99% by weight. %, respectively, 99 to 1 wt. % by the total amount of components (b - [) and (b2). If the component (b- |) contains one or more nitroxyl compounds of formula Illa, which in terms of e.g. when subjected to distillation of a vinyl-containing compound, the compound (s) are considered to be very volatile; therefore, they meet the steam pressure criteria described at the boiling point of the lowest boiling compounds with vinyl groups as an integral part ( A)

913.99-PB represent a few percent or tens of percent of

the vapor pressure of this compound with vinyl groups such that the component part (b- |) has a value below 99 wt. and, accordingly, the part of the component (b3) is adjusted above 1 wt. %.

When the component (b- |), contrary to the case described above, contains nitroxyl compounds with less volatility, their portion is preferably adjusted to be larger than the total mixture of components (b- |) and (b3) .

By adding aromatic nitro compounds as component (b3) to the stabilizer (B), the ratio between the amount of component (b3) and the amount of nitroxyl compounds (the sum of the amounts of components (b- |) and (b3)) may vary by any way. Since nitroxyl compounds are most often relatively expensive, their part in the stabilizer should still be as small as possible.

Typically such mixtures consist of 0.05 to 4.5 wt. % of the nitroxyl compound (sum of components (bj) and (b3)) and 95.5 to 99.95 wt. % of the aromatic nitro compound wherein the parts are taken relative to the total amount of components (bj), (b ₂ ) and (b ₃ ).

If iron compounds such as component (bg) are added to the stabilizer (B) in addition to components (b- |) and (b ₂ ), then their portion is usually 1 ppm to 5 wt. %, preferably 10 ppm to 3 wt. % relative to the total amount of components (b- |), (b ₂ ) and (bd).

When, in addition to the nitroxyl compounds, the components (b3) as well as (bb) are present, their parts are calculated as stated above for the stabilizers (B),

913.99-PB

which contain nitroxyl compounds (as components (b- |) and (b ₂ )) and aromatic nitro compounds (as component (b ₃ )), respectively, iron compounds (as component (bd)). For a stabilizer (B) that contains components (b- |), (b ₂ ), (b ₃ ) and (bd), thus, the fraction of component (b ₃ ) relative to the sum of components (bj), (b ₂ ) and (b ₃ ) can be chosen arbitrarily. The common part of component (b ₃ ) relative to the sum of components (b - |), (b ₂ ) and (b ₃ ) is from 95.5 to 99.95 wt. %. The fraction of component (bg) relative to the sum of components (b- |), (b ₂ ) and (64) is typically from 1 ppm to 5 wt. %, preferably 10 ppm to 3 wt. %.

If, for example, other stabilizers are added to the stabilizer (B), as mentioned above, then with respect to the fraction of the entire quantity of components (bf), (b ₂ ), optionally (b ₃ ) and / or case F4), the amount of stabilizer (s) is from 0.01 to 20 wt. %.

The stabilizer (B) is present in the mixture of substances according to the invention typically in an amount of 0.0002 to 5 wt. %, preferably from 0.0005 to 0.5 wt. % by total mixture of component (A) and stabilizer (B).

Under inert conditions such as e.g. in a nitrogen atmosphere, it is preferable for the stabilizer (B) to contain at least one nitro compound as component (b ₃ ), and optionally one iron compound as component (64). The appropriate ratio of the nitroxyl compound to the component (b ₃ ) thus depends on the individual boundary conditions, such as e.g. from the chemical nature of the stabilizing compounds constituting component (A), from the temperature limits maintained during distillation (by the way, they are

913.99-PB

important in terms of volatility and thus the distribution of the components (b- |) and (b3) between the gaseous and liquid phases) or also the (residual) oxygen content of the mixture used, it is still possible for one skilled in the art , subject to appropriate circumstances, by preliminary attempts to determine the optimum ratio of components. Typically, stabilizers (B) can provide a good effect at the content of the above-mentioned content of 95.5 to 99.95 wt. parts of an aromatic nitro compound.

If the compounds (A) to be stabilized are exposed to an atmosphere that often contains (residual) oxygen, then some of the nitro compounds must be reduced or this additive can be avoided at all. It is very desirable, precisely from the point of view of safety when dealing with such inhibitors, and from the point of view of reducing any possible adverse effect on the environment. Thus, the nitroxyl compounds themselves (i.e. stabilizers (B) containing only the components (b-) and (b3)), and even more strongly the iron-containing stabilizers (B), without the addition of nitro compounds in the content of oxygen from about 0.5 ppm to 10,000 ppm, which is common in industrial distillation columns, exhibit a very good stabilizing effect on compound (A) against unwanted premature polymerization.

The stabilizer (B), optionally in admixture with nitro compound (b3) and / or iron compound (b4) and / or stabilizers, is added to the vinyl group containing compounds (A) before or during purification or distillation as a suspension or as a solution, using a suitable solvent

913.99-PB • · · ·

or a mixture of solvents in an effective amount to prevent premature polymerization. In some cases, it may also be necessary to have the components (b- |) and (b2) of the stabilizer (B), and optionally a nitro compound (b3) and / or an iron compound (64) and / or one or more of the above stabilizers should be added separately and preferably at different points in the system.

In addition, partial mixtures may be necessary, e.g. on the one hand, a mixture of groups of components, e.g. optionally, a mixture of the component (63) with the nitro compound (63) and / or the iron compound (bg) and / or optionally with other stabilizers and, on the other hand, the component (bj) being added separately and, preferably, different places in the system.

Suspensions or solutions of stabilizers (B) are preferably obtained with water. In addition, it is preferable to add alkanols, such as methanol, ethanol, propanol, as well as normal, iso- or tert-butanol, in admixture with water. These alcohols or mixtures thereof with water are preferably used in the case of the use of the corresponding acrylic acid esters as well as alkyl acrylic acid, i. in the case of vinyl groups of formula II.

In addition, ketones, such as e.g. ketones, in combination with alcohols and water are used as suspending or dissolving agents. acetone, methyl ethyl ketone, methylpropylketone, methylbutyl ketone, diols, such as glycol or propylene glycol, as well as their alkylmono- or di-dieters, oligomers or polymeric ethylene glycols (polyethylene glycols) and propylene glycols (polypropylene glycols), as well as diamine alkylenes,

913.99-PB

or propylenediamine, as well as their alkylmono- or diimino ethers, oligomers and polymeric ethylenediamines (polyethyleneimines), as well as their alkylimino ethers. Naturally, the solvents or suspending agents used may also be the compounds (A) used or mixtures thereof.

In addition, mixtures of crude products may be added for this purpose. Can be used e.g. so-called furnace oil - a mixture de-dehydrating ethylbenzene containing primarily styrene, ethylbenzene, toluene and other substituted aromatic substances, after distillation purification, so that this mixture can be used as a solvent and / or as suspending agent. Naturally, ethylbenzene or toluene as pure substances may also be used as solvents and / or suspending agents.

The stabilizers (B) according to the invention can also, in the form of pure substances or in the form of a solution or suspension, be used mainly to inhibit premature polymerization, preferably of radical polymerizing compounds, and exhibit their stabilizing action over a wide temperature range. They are active at any of the usual storage temperatures, from -50 to + 50 ° C. The range of stabilization pressures is not critical. The stabilizers operate under normal pressure as well as under or under pressure.

913.99-PB

Examples of carrying out the invention

The following embodiments should elucidate the inventive thought without, however, limiting the scope of the invention,

Table 1 shows the various compounds of formula Illa with their pressure-dependent boiling points (eigenvalues).

In addition, said compounds mean:

Tempo: Oxo-tempo:

and the compounds having the corresponding substituent R c

the formula: 0— R Ϊ H ₃ C \ H ₃ C ^{X CH3} axis f ^X CH, o

which are referred to as Ac-Tempol when R = acetyl;

Tempol when R = H; Me-Tempol when R = methyl; Et-Tempol when R = ethyl and TMS-Tempol when R = trimethylsilyl.

The compounds listed in Table 1 have, at hPa pressures, the corresponding boiling points, which are given as a numerical value in ° C.

Table

Oxo-Tempo 60.2 70.2 81.1 98.1 102.5 115 TMS-Tempol 609 71 .4 82.8 110.4 105 117.8 Et-Tempol 56.1 66.2 77.2 94.2 98.7 CM M © -Tempol 49.1 59.2 70.2 87.3 91 .7 CM Mo Tempol 89.1 99.56 CO o 128.1 132.6 145 Ac-Tempol 71.2 82 93.5 111.1 115.6 128.1 Tempo 22.9 32,6 43,2 59.7 64 76.1 Pressure (hPa) 0.5 CM 5.3 6.7 12.5

913.99-PB ·· ♦ ···

Table 2 shows compounds with vinyl groups corresponding to formulas 1a and 1b, and Table 3 shows compounds with vinyl groups corresponding to formula II, respectively with their boiling points. The brackets indicate, respectively, the numerical values (in hPa) of the corresponding vapor pressures at the indicated boiling temperatures, if these are pressures that deviate from the normal pressure (1013 hPa).

Tables 2 and 3 also list the literature sources from which the boiling points were taken. If the volume and year are indicated in addition to the reference page, the data is taken from Roempp-Chemielexikon (Georg Thieme Verlag, StuttgartNew York). If only the page is specified, then the data is taken from Chemiker-Kalender (3rd Auflage, Springer-Verlag, Berlin, Heidelberg, New York, Tokyo (1983)).

Table 2

Compound Boiling point in ° C Literary source styrene 145.8 Volume 5, pp. 4355/6 (1992) α-methylstyrene 165 Volume 4, page 2761, (1991) vinyl toluene 1 72 (t: p = 60:40) * Volume 6, Page 4927 (1992) divinylbenzene 195 (t: p = 75:25) * Volume 2, pp. 1018/9 (1990) 2-vinylpyridine 49-51 (16) Volume 6, Page 4926 (1992) 4-vinylpyridine 62-65 (19) Volume 6, pp. 4926, (1992) 2-methyl-4-vinylpyridine 181 Volume 4, page 2763, (1991)

* Parts of m- and p-isomers mixed with indicated boiling point

913.99-PB • ·

Table 3

Compound Boiling point in ° C Literary source acrylonitrile 77.5 page 199 acrylic acid 141 page 199 methyl acrylate 80.5 page 199 ethyl acrylate 99-100 page 199 butyl acrylate 145 page 199 methacrylic acid 159 (989) page 319 methyl methacrylate 100.3 page 319 ethyl methacrylate 116.5 page 319 vinyl methyl ether 5.5 Volume 6, Page 4924 (1992) vinyl ether 35.5 Volume 6, page 4924 (1992) vinyl-p-butyl ether 94 Volume 6, page 4924 (1992) vinyl-Ϊ-propyl ether 83 Volume 6, Page 4924 (1992) 1-vinyl-2-pyrrolidone 215, 96 (19) Volume 6, Page 4926 (1992) N-vinylformamide 84.2 (12.5) own measurement

If, for example, styrene is to be stabilized during distillation in both liquid and vapor form and distillation is carried out at normal pressure, then a liquid nitroxyl compound (b- |) should be selected according to the invention to be found at the target for styrene, a boiling point of 145.8 ° C, a pressure of 0.01 to 50% relative to the vapor pressure of styrene (1013 hPa). From Table 1 it can be seen immediately that the Tempol compound is steam

913.99-PB

pressure of 12.5 hPa at 145 ° C («145.8 ° C), so that it meets these requirements (12.5 / 1013 = 1,2%).

In order to determine whether the use of the Tempo compound is appropriate, the following should be done: according to Table 1, the Tempo compound at a temperature of 76.1 ° C has a vapor pressure of 12.5 hPa. According to the Clausius-Clapeyron equation, in its approximate form:

L

In p (T ₂ ) - In p (T _n ) = —- (1 / T _L - 1 / T ₂ ),

R wherein T- | and T ₂ are different boiling points, in particular T - 1 = 76.1 ° C and T ₂ = 145.8 ° C, p (T ^) and p (T ₂ ) are respectively the different vapor pressures, here in particular p (Tj) = 12.5 hPa and p (T ₂ ) is the required vapor pressure, L is the heat of evaporation, In is the natural logarithm at base e and R is the gas constant (8.314 Jmol '^ K' ^) and this equation makes it possible to calculate the vapor pressure p (T ₂ ) of the nitroxyl compound. Using the Pictet-Trouton rule, the heat of evaporation L at 76.1 ° C and 145.8 ° C is estimated as follows:

L (76.1 ° C) «88 J. mol ' ¹ K ¹ . (273.15 + 76.1) K = 30734 J. mol- ¹ and

L (145.8 ° C). 88 J.moHK · ¹ . (273.15 + 145.8) K = 36867.6

J.moM

If these values are applied respectively to L in the above form of the Clausius-Clapeyron equation, then the Tempo compound is obtained at a temperature of 145.8 ° C with a vapor pressure between 72.7 hPa (L (76.1 ° C)) and 103.3 hPa ( L (145.8 · · · · · · · · · · · · · · · · · · · · · · · ·

913.99-PB ° C)). Both values meet the criteria of the invention (72.7 / 1013 = 7.2% and 103.3 / 1013 = 10.2%, respectively).

Tempo can therefore be used to stabilize styrene under normal pressure distillation as a component (bj), as well as the other nitroxyl compounds listed in Table 1. If styrene is to be distilled under reduced pressure, as is customary, then the pressure / temperature ratio that applies to styrene can be determined by equality (taken by Ullmanns Encykl. d. Techn. Chem., Bd. 22, Verlag Chemie Weinheim, 4. At I., p. 294 (1982))

1457.3

Ig p (T) = 7.0916 ...................

211.45 + T in which p (T) denotes the pressure in hPa, at a temperature на expressed in ° C and Ig is the logarithm of base 10. The procedure for determining one suitable component (bj) then proceeds analogously to that described above. .

For other compounds containing vinyl groups, the vapor pressure data in analytical form can often also be calculated by one corresponding equality, or they can be easily found.

If, for example, a mixture of compounds with vinyl groups such as e.g. a mixture of styrene and divinylbenzene in the vapor phase, the boiling points at normal pressure are 145.8 ° C and 195 ° C, respectively (the latter temperature is for a mixture of t- and p-isomers in the ratio 75:25) / temperature of the lowest boiling compound, in the case of styrene, serve as determinants for the choice of the volatile nitroxyl compound as component (b- |) and

913.99-PB ·· · · · · · · · · · · · · · · · · · · · · · · ·

·· ·· • · • • • · • • • • · • · ·· • ··· • · · · · • · • • ··

the relevant data of the isomeric mixture of divinylbenzenes as the highest boiling compound serve as determinants for the selection of the volatile nitroxyl compound as component (b ₂ ). If more volatile nitroxyl compounds are to be used, those with the lowest vapor pressure (i.e., the highest boiling nitroxyl compounds) at appropriate temperatures may also meet the criteria of the invention.

When compounds having too high volatility are used as component (b), there is a risk that these nitroxyl compounds will pass (in parts) into the distillate and there will hinder the subsequent conversion (e.g. polymerization) of the purified vinyl containing compounds groups.

Without other detailed evaluation or calculations as outlined above, it can be immediately understood, by comparing Tables 2 and 3 with Table 1, that to stabilize almost all the vinyl group compounds described in Tables 2 and 3 or mixtures thereof , could be used as component (b- |) of all the nitroxyl compounds of Table 1 or mixtures of these compounds.

In the case of vinylmethyl ether, which has a boiling point of 5.5 ° C at normal pressure, the vapor pressure of the Tempol compound at this temperature may already be too low, i. lower the lower limit of the selection criteria. One evaluation, as already done above as an example, shows for this nitroxyl compound a vapor pressure at 5.5 ° C between 0.083 and 0.17 hPa and thus related to the vapor pressure of the vinylmethyl ether913.99-PB. (1013 hPa) it is calculated that the percentages are from 0.0082 to 0.017%. Thus, the fraction of this nitroxyl compound for stabilizing the vinyl methyl ether in the gas phase may be too small. This should be decided on the basis of basic data and experiments, and naturally, in this temperature range, the trend towards radical polymerization is significantly reduced.

Since the vapor pressure curves of the vinyl group compounds and those of the volatile nitroxyl compounds suitable for their vapor phase stabilization generally move at least in wide pressure / temperature ranges far from parallel or approximately parallel, should at one or more pressure / temperature pairs be found, they should also be valid at a deviating pressure / temperature ratio, with the potential suitability of the nitroxyl compound.

Where additives of aromatic nitro compounds and / or iron compounds as components (b3) and (64) are contemplated to be added to other stabilizers, they are generally used compounds which, at the pressure / temperature ratios in question, are slightly volatile or even volatile. However, it may be desirable here, as with the nitroxyl compounds representing the components (b-) and (bp), combinations of the corresponding volatile and volatile compounds are added. The selection criteria are preferably completely analogous to the selection criteria for the nitroxyl compounds representing the components (bj) and (b ₂ ) · ··

913.99-PB ·· ·· • · ·· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·

It may also be noted that the partial pressures actually present in the gas phase of the components (b- |), in the case (b3) and / or in the case (bd), also of the possibly stabilizers, due to the intramolecular interaction in the gas as well as in the liquid phase may deviate from the expected Henry-Dalton law values and thus the composition of the liquid phase. Since, in addition, the vapor pressures of the components in the gas phase are not generally regarded as ideal gas, often calculations can only aim to obtain a rough estimate of the quantitative ratios of components to each other in the gas space. However, here, most often, by analyzing the vapor phase (condensed vapor) and the liquid phase, easy and rapid information on the respective formulations can be obtained and these formulations correlate with the effects of stabilization.

In addition, by reacting the components with one another or with compounds containing vinyl groups, it can be

obtain more volatile derivatives or volatile compounds to become more volatile. In these cases, only the ability of different iron compounds (as a possible component (64)) to form π-complexes with compounds containing vinyl groups or with aromatic nitro compounds should be considered.

Claims (10)

1. A mixture of substances, characterized in that it contains: (A) compounds with one or more vinyl groups, (B) a stabilizer containing (b-) a nitroxyl compound of a secondary amine which does not contain hydrogen atoms at α-C atoms, the vapor pressure of which at boiling point of the lowest boiling compound with vinyl groups of component (A) is from 0.01 to 50% relative to the vapor pressure of the lowest boiling compounds with vinyl groups of component (A) or a mixture of nitroxyl compounds of secondary amines which do not contain hydrogen atoms at α-C atoms in which the vapor pressure of the highest boiling nitroxyl compound at the boiling point of the lowest boiling compound with vinyl groups of component (A) is from 0.01 to 50% relative to the vapor pressure of the lowest boiling compound with vinyl groups of component (A), (b2 ) a secondary amine nitroxyl compound which does not contain hydrogen atoms at the α-C atoms, the vapor pressure of which at the boiling point of the highest boiling compound with vinyl groups of component (A) is less than 0.01% relative to the steam pressure at the highest boiling point it a compound with vinyl groups of component (A) or a mixture of secondary amine nitroxyl compounds that do not contain hydrogen atoms at α-C atoms in which the vapor pressure of the lowest boiling nitroxyl compounds at the boiling point of the high boiling compound with vinyl groups of component (A) is less than 0.01% 913.99-PB ·· ·· • · · ·· ·· • • • • ·· · · • • • · • · • · • · • • • · • • • • · • · • ·· • • · · e • • • • · • • ·· • · ··· ···· • · ·· with respect to the vapor pressure of the highest boiling compound having the vinyl groups of component (A), with (b) and (b2) respectively having in mind the vapor pressure of the corresponding pure nitroxyl compound and the vapor pressure of the corresponding pure vinyl aromatic compound, at the boiling point of that pure vinyl aromatic compound, (b3) optionally one or more aromatic nitro compounds, (F4) optionally one or more iron compounds. 2. A mixture of substances according to claim 1, characterized in that it contains, as a component (A), vinyl group compounds of formula la 1a, Wherein R ¹ is hydrogen, C 1 -C 4 -alkyl, C 2 -C 4 * alkenyl, carboxy, formyl, sulfo, hydroxy, amino or nitro, R 2 is C ₂ -C ₄ -alkenyl and / or vinyl groups of formula lb in which R ³ is hydrogen, C 1 -C 4 -alkyl, R ⁴ is C2-C4-alkenyl. 913.99-PB Composition of substances according to claim 1, characterized in that it contains, as a component (A), vinyl group compounds of formula II CH ₂ = CZ ⁴ -QZ ¹ (lb) in which Q means a simple chemical bond, oxygen or -NZ2- group, Oh II c “ ¹ means radicals WITH ^OR ” Ζ2, Ζ4 are each hydrogen, C1-C4 alkyl, Z ³ is hydrogen, hydroxy, cyano, C 1 -C 3 -alkoxy, C 1 -C 3 -alkyl or a residue which together with Z 2 or Z ⁴ forms a saturated or unsaturated C 3 -, C 4 -, C 5 - or C 3 -alkylene a bridge in which up to two of the carbon atoms which are not adjacent to each other can be replaced by N, NH, N (C 1 -C 4 -alkyl), N (C 1 -C 5 -aryl) or oxygen. A mixture of substances according to claims 2 or 3, characterized in that it contains, as component (b-), one or more compounds of formula Illa in which R ⁵ is hydrogen, Λ · R ⁶ is hydrogen, hydroxy, C 1 -C 4 -alkoxy, C 1 -C 3 -acyloxy, three (C 1 -C 4 -alkyl) silyloxy or CR ⁵ R ⁶ denote together a carbonyl group and as a component (b 3) one or more compounds of formula 111 b 913.99-PB nx dream ₃ n ₃ with dream ₃ in which X is oxygen or R ⁷ -N, A is Οθ-Οή 3-alkylene, a, <o-bis (carbonyloxy) -C 1 -C 3 -alkylene, α, ω-Οθ-Ο-ι 3-diacyl, 1,2-, 1,3- or 1 , 4-phenylene, phthaloyl, isophthaloyl or terphthaloyl, R ⁷ is hydrogen, C | -C 4 -alkyl or C | -C-acyl. Stabilizer (B) according to claim 1, characterized in that it contains, as component (b-j), one or more compounds of formula IIIa and, as component (b3), one or more compounds of formula 111b. Stabilizer (B) according to claim 5, characterized in that it contains, as an additional component (b3), one or more aromatic nitro compounds. Stabilizer (B) according to claim 5, characterized in that it contains, as an additional component (bg), one or more iron compounds. · · · · · · · · · · · · · · · · · · · · · 913.99-PB • ·· ·· ·· ·· · · • · • · • · • · • · • · · • · · • · · • · • • ··· ···· ·· ·· 8, a stabilizer (B) according to claim 5, characterized in that it contains, as an additional component (b3), one or more aromatic nitro compounds and, as an additional component (bg), one or more iron compounds. 9. A method for inhibiting premature polymerization of vinyl group compounds according to claims 1 to 3, characterized in that an effective amount of stabilizer (v) is added to the vinyl group (A) compounds before or during their purification or distillation. B) according to claims 1 or 5 to 8. 10. A method for inhibiting premature polymerization of vinyl group compounds according to claims 1 to 3, characterized in that the stabilizer components (B) are added to the vinyl group compounds (A) before or during their purification or distillation. ) according to claims 1 or 5 to 8 or at least two groups of these components.